The large-scale analysis of gene expression profiles was the first hallmark in the transition from structural genomics to functional genomics. Genomic-scale expression profiling experiments require large technical and computational investments to facilitate both experimentation and the analysis of the large datasets produced. These investments are beyond the capabilities of most laboratories or small groups. To provide access to these important technologies, the DNA Microarray Core, operating within the Vanderbilt Microarray Shared Resource (VMSR) has been established with major support from the DDRC, the Diabetes Research and Training Center, the Vanderbilt-Ingram Cancer Center (VICC) and the Vanderbilt University Medical Center Office of Research. The objectives of this Core are to assist investigators in performing genome-scale expression profiling experiments and to provide informatics support in the analysis of the gene expression data sets. Services offered in the Core are in two classes: experimental support and data support. Experimental support includes the generation of high-density mouse, human, rat, and yeast DNA microarrays containing from 5,000 to 15,000 elements, RNA processing, fluorescent cDNA target production and high-density array hybridization. Personnel of this core provide consultation in the generation of smaller, more specific custom or "boutique" arrays that may be directed toward a specific cellular process or condition. Data support includes the scanning and image analysis of the hybridized array to generate raw data sets, the processing of the raw data sets to produce a normalized and refined gene expression profile, and the support of higher-order statistical analysis such as hierarchical or K-means clustering and multidimensional scaling. Since August 2000, the Core has generated over 300 quality expression profiles from mouse and human microarrays containing over 5,000 elements each. The Core has recently expanded its capabilities to offer mouse arrays containing 15,000 elements, human arrays containing up to 10,000 elements, and full-genome yeast oligonucleotide arrays.